The action takes place at the time of Charlemagne’s war against the Saracen King of Africa, Agramante who is invading Europe to avenge the death of his father, Troiano. Orlando, one of Charlemagne’s soldiers, is forgetting his duties pursuing his unrequited love for the pagan princess Angelica, Queen of Cathay, who is instead in love with Medoro, a Saracen knight.

Act I

The magician Zoroastro tries to convince the knight Orlando to go to war and not waste time chasing love (“Lascia Amor”). Orlando decides instead that Glory can be also achieved through the passions of Love (“Non fu già men forte Alcide”). In a forest, the shepherdess Dorinda is lamenting the lack of passion in her life, when she suddenly sees Orlando carrying a recently rescued princess, Isabella (“Ho un certo rossore”). Angelica, the object of Orlando’s love, is actually in love with the African prince Medoro, whose wounds were healed while once being hosted by Dorinda (“Ritornava al suo bel viso… Chi possessore… Se ’l cor mai ti dirà”). Zoroastro warns Angelica that Orlando is after her. With a magic trick, he hides Medoro behind a fountain while Orlando approaches Angelica. Orlando leaves, and the two lovers can finally declare their love. To soothe Dorinda’s disdain, Angelica gives her a jewel (Trio: “Consolati o bella”).

Act II

Dorinda tells Orlando that Angelica is in love with Medoro (“Quando spieghi i tuoi tormenti”), and shows him the jewel that he actually once gave to Angelica (“Cielo! Se tu il consenti”). Zoroastro warns Angelica and Medoro that Orlando is after them, driven by jealousy (“Tra caligini profonde”). Before leaving, the two lovers carve their names in a laurel tree (“Verdi allori”). When Orlando sees those inscriptions, he first threatens to kill Angelica, but Zoroastro takes her away on a cloud. Jealousy destroys Orlando’s mind, until Zoroastro saves the knight from his own madness by bearing him off on a chariot (“Ah, Stigie larve.. Vaghe pupille”).

Act III

Dorinda is providing shelter to Medoro (“Vorrei poterti amar”). Orlando arrives, and—still insane—declares his love for Dorinda, whom he believes is Venus (“Unisca amor in noi… Già lo stringo”). The shepherdess then tells Angelica of Orlando’s madness (“Così giusta è questa speme”). Zoroastro reappears with his genii and makes the scene change into a cavern, promising to restore Orlando’s mind (“Sorge infausta una procella”). Dorinda now tells Angelica that Orlando has destroyed her cottage and killed Medoro. Angelica is inconsolable and the appearance of Orlando only worsens the situation (“Finchè prendi ancora”). Orlando tries to throw her into the cavern, but Zoroastro transforms the scene into the Temple of Mars and he falls asleep (“Già l’ebro mio ciglio”). The magician now calls for an eagle carrying a liquid that can restore Orlando’s mind. When he awakes, Dorinda tells the hero that he killed Medoro, and for this Orlando attempts suicide. However, Zoroastro has in fact saved Medoro, and the opera ends with a celebration of Glory and Love (“Trionfa oggi ’l mio cor”).